1. Technical Field of the Invention
The present invention relates to a semiconductor device and to a method of manufacturing a semiconductor device. More particularly, the present invention relates to a technique effectively used for reducing damage, to elements which are provided in a semiconductor device, in the process of manufacturing the semiconductor device.
2. Description of the Related Art
Various semiconductor devices are mounted on electronic equipment. Recently, electronic equipment has been downsized. In accordance with downsizing of electronic equipment, a semiconductor device having a three-dimensional mounting structure has been proposed. Examples of the three-dimensional mounting structure of the prior art are disclosed in Japanese Unexamined Patent Publication Nos. 10-223833 and 10-303364.
According to the above patent publications, there has been proposed a three-dimensional mounting structure in which a plurality of semiconductor elements are laminated in the vertical direction. Each semiconductor element composing this three-dimensional mounting structure mainly includes a silicon substrate, on the surface of which elements such as transistors are formed. In this silicon substrate, metallic plugs electrically connected with the above elements are embedded in the thickness direction of the silicon substrate. Electric power is supplied and signals are inputted into the elements through these metallic plugs.
In this connection, according to the above patent publications, the metallic plugs in the silicon substrate are formed as follows. After elements have been formed on one of the faces of the silicon substrate, holes not penetrating the silicon substrate are formed on this face, that is, holes not penetrating the silicon substrate are formed on the face of the silicon substrate on which the elements have already been formed, and then these holes are charged with metal.
However, the above method, in which the holes are formed in the substrate after the elements have already been formed on it, is disadvantageous in that the elements formed in the periphery of the holes are damaged when the holes are formed. Therefore, the yield of manufacturing a semiconductor device is deteriorated.
The present invention has been devised in order to solve the problems caused in the prior art.
Accordingly an object of the present invention is to provide a method of manufacturing a semiconductor device by which the yield of manufacturing a semiconductor device can be enhanced.
According to the present invention, there is provided a method of manufacturing a semiconductor device, said method comprising the following steps of: forming first holes not penetrating a support side semiconductor substrate on one of faces of the support side semiconductor substrate; forming a ground insulating film on one of the faces of the support side semiconductor substrate and also on side walls and bottom sections of the first holes; forming primary connection plugs by charging a first metal into the first holes; forming a semiconductor film on one face side of the support side semiconductor substrate via an intermediate insulating film; forming elements on the semiconductor film; exposing bottom faces of the primary connection plugs by polishing the other face of the support side semiconductor substrate; forming second holes extending from the element forming face of the semiconductor film to the primary connection plugs; and forming auxiliary connection plugs for electrically connecting the elements with the primary connection plugs by charging a second metal into the second holes.
According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, said method comprising the following steps of: forming first holes not penetrating a support side insulating substrate on one face of the support side insulating substrate; forming primary connection plugs by charging a first metal into the first holes; forming a semiconductor film on one face side of the support side insulating substrate via an intermediate insulating film; forming elements on the semiconductor film; exposing bottom faces of the primary connection plugs by polishing the other face of the support side insulating substrate; forming second holes extending from an element forming face of a semiconductor film to the primary connection plugs; and forming auxiliary connection plugs for electrically connecting the elements with the primary connection plugs by charging the second metal into the second holes.
Next, the operation of the present invention will be explained below.
The method of manufacturing a semiconductor device of the present invention includes the following steps (a) to (h).
(a) Step of forming the first holes, which do not penetrate the support side semiconductor substrate, on one of the faces of the support side semiconductor substrate.
(b) Step of forming a ground insulating film on one of the faces of the support side semiconductor substrate and also on the side walls and the bottom sections of the first holes.
(c) Step of forming primary connection plugs by charging the first metal into the first holes after the ground insulating film has been formed.
(d) Step of forming a semiconductor film on one face side of the support side semiconductor substrate via an intermediate insulating film after the primary connection plugs have been formed.
(e) Step of forming elements on the semiconductor film after the semiconductor film has been formed.
(f) Step of exposing bottom faces of the primary connection plugs by polishing the other face of the support side semiconductor substrate after the elements have been formed.
(g) Step of forming the second holes extending from the element forming face of the semiconductor film to the primary connection plugs.
(h) Step of forming auxiliary connection plugs for electrically connecting the elements with the primary connection plugs by charging the second metal into the second holes.
According to the above manufacturing method, after the step of forming the first holes (step (a) described above), the step of forming the elements (step (e) described above) is executed. Therefore, when the first holes are formed, no elements are damaged. Accordingly, the yield of manufacturing the semiconductor device can be enhanced.
In step (a) described above, wiring grooves may be formed on one of the faces of the support side semiconductor substrate. In the step of forming the primary connection plugs (step (c) described above), these wiring channels are charged with the first metal and become the primary wiring. However, this primary wiring is embedded in the support side semiconductor substrate. Therefore, irregularities on the support side semiconductor substrate are small compared with a case in which wiring is provided on the support side semiconductor substrate.
Further, in step (b) described above, a wiring embedding insulating film having opening sections for minute wiring may be formed on a ground insulating film after the ground insulating film has been formed. Into these opening sections for minute wiring, the first metal is charged in the step of forming the primary connection plugs (step (c) described above), so that these opening sections for minute wiring become minute wiring. These opening sections for minute wiring are formed on the wiring embedding insulating film, the thickness of which is smaller than that of the support side semiconductor substrate. Therefore, these opening sections for minute wiring are remarkably minute compared with the wiring grooves formed on the support side semiconductor substrate. For the above reasons, the minute wiring is very minute compared with the primary wiring.
In this connection, the semiconductor film is formed in step (d) described above, however, the semiconductor film may be formed so that it can have the structure of SOI. In order to form the semiconductor film having the structure of SOI, first, an element side semiconductor substrate, on the surface of which an intermediate insulating film is formed, is prepared. Then, an intermediate insulating film side of the element side semiconductor substrate is stuck onto one of the faces of the support side semiconductor substrate. After that, the thickness of the element side semiconductor substrate is decreased, so that the element side semiconductor substrate can be formed into the above semiconductor film.
By the above steps, it is possible to form a semiconductor film of small thickness on the intermediate insulating film. This structure is the structure of SOI (Silicon On Insulator) itself. That is, the above intermediate insulating film functions as an embedding insulating film, and the above semiconductor film functions as a film of SOI.
A step of forming a surface flattening insulating film may be formed on one of the faces of the support side semiconductor substrate and also a step of forming a surface flattening insulating film may be provided before the semiconductor film is formed in the step of forming the semiconductor film (step (d) described above). Due to the foregoing, the semiconductor film can be formed on a flattened surface. Especially when the element side semiconductor substrate is stuck as described above, it is possible to stick the element side semiconductor substrate onto the surface flattening insulating film without leaving any gap between them.
In this connection, in the above case, the support side semiconductor substrate is used, however, like another method of manufacturing a semiconductor device of the present invention, it is possible to use the support side insulating substrate instead of the support side semiconductor substrate. In this case, after the first holes have been formed on the support side insulating substrate, it is possible to provide a step of forming a film for enhancing the adhesion property between the support side insulating substrate and the first metal on the side walls of the first holes. Due to the foregoing, it is possible to prevent the first metal from separating from the support side insulating substrate, so that the reliability of the wiring can be enhanced.
In a case in which either the support side semiconductor substrate or the support side insulating substrate is used, in the step of forming the primary connection plugs (step (c) described above), it is possible to provide a step, in which a barrier metal layer for covering exposed faces of the primary connection plugs is formed, after the primary connection plugs have been formed. When this barrier metal layer is formed, it is possible to prevent the first metal from diffusing from the primary connection plugs onto the film formed on the barrier metal layer.
According to still another aspect of the present invention, there is provided a semiconductor device comprising: a support side semiconductor substrate having a first hole penetrating thereof; a semiconductor film incorporated therewith an element, said semiconductor film having a second hole penetrating thereof and being laminated on said support side semiconductor substrate; a primary connecting plug comprising a first metal filled in said first hole; and an auxiliary connecting plug comprising a second metal filled in said second hole, said auxiliary connecting plug electrically connecting said primary connecting plug with said element.
According to further aspect of the present invention, there is provided a semiconductor device comprising: a support side insulating substrate having a first hole penetrating thereof; a semiconductor film incorporated therewith an element, said semiconductor film having a second hole penetrating thereof and being laminated on said support side insulating substrate; a primary connecting plug comprising a first metal filled in said first hole; and an auxiliary connecting plug comprising a second metal filled in said second hole, said auxiliary connecting plug electrically connecting said primary connecting plug with said element.